The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In the automotive industry, environmental concerns require a continued reduction in the amount of particulates, including soot particulates and non-combusted particulates, discharged from engines. Various attempts have been made to decrease these particulate emissions from the use of fuels, such as diesel. Typical catalytic converters often do not work well with some engines, since the temperatures within them are too low to effectively burn carbon, oil, and unburned fuel particles. Currently, research has been performed using exhaust gas filtering systems having a particulate filter inserted in an exhaust pipe of the engine to collect the particulates. In general, the particulate filter is made of a porous ceramic body, which defines a plurality of exhaust gas passages therein. When exhaust gas passes through porous walls of the particulate filter, which define the exhaust gas passages, the particulates are adsorbed and collected by the porous walls of the particulate filter.
When the collected particulates are accumulated in the particulate filter, pressure loss is increased, and the engine performance is deteriorated. Thus, the collected particulates need to be combusted and removed from the particulate filter to regenerate the particulate filter at appropriate timing. The regeneration of the particulate filter is performed by increasing the temperature of the particulate filter through a heating means, such as a burner or a heater or through supply of hot exhaust gas to the particulate filter in post fuel injection.
In view of the above, there remains a demand for a passive exhaust filter system that can successfully remove particulate matter. It is also desirable that the filter system be regenerable and reliable over long periods of time without maintenance.